Electronic Device Display Structures

ABSTRACT

An electronic device may have a housing in which a display is mounted. A gasket may be mounted in a groove between the display and housing. The gasket may contain an embedded stiffener. Corner brackets may be installed in the corners of the housing. The housing may have inner and outer concentric ribs. Recesses in the housing may be configured to receive the corner brackets. The recesses may be formed between the inner and outer concentric ribs. Gap filling structures such as a foam layer may be interposed between a rear housing wall and a display backlight unit. Display color variations may be corrected by using a backlight unit having an array of light-emitting diodes of different colors. An electrostatic discharge protection layer may be grounded to a housing using conductive tape. Black edge coatings and adhesive-based structures may block stray light. Camera window regions may be supported using adhesive.

This application is a division of U.S. patent application Ser. No.14/754,455, filed Jun. 29, 2015, which is a division of U.S. patentapplication Ser. No. 13/629,503, filed Sep. 27, 2012, which claims thebenefit of U.S. provisional patent application No. 61/657,232, filedJun. 8, 2012, all of which are hereby incorporated by reference hereinin their entireties.

BACKGROUND

This invention relates to electronic devices and, more particularly, tostructures for electronic devices such as display structures.

Electronic devices such as portable computers and cellular telephonestypically have displays. It can be challenging to incorporate displaystructures into an electronic device. If care is not taken, electronicdevice display structures will be undesirably bulky or may haveperformance problems associated with display robustness, coloruniformity, electrostatic discharge protection, and componentintegration.

It would therefore be desirable to be able to provide improved displaystructures in electronic devices.

SUMMARY

An electronic device may have a housing such as a metal housing. Adisplay such as a liquid crystal display may be mounted within thehousing. A groove may separate the housing from the display. A gasketmay be mounted within the groove. The gasket may be formed from anelastomeric material. A recess in the gasket may be configured toreceive an edge of the display. The gasket may have protrusions such asa lower protrusion that is attached to the housing of the electronicdevice with adhesive and an upper protrusion that covers an edge portionof the surface of the display. A portion of the gasket may contain anembedded stiffener such as a metal stiffening structure.

Corner brackets formed from sheet metal members may be installed in thecorners of the housing. The housing may have inner and outer concentricribs. Recesses in the housing may be configured to receive the cornerbrackets. The recesses may be formed between the inner and outerconcentric ribs.

Gap filling structures may be interposed between a rear housing wall inan electronic device housing and a display backlight unit associatedwith a display. A gap filling structure may be formed from plasticmember or a layer of foam.

Variations in the color of display pixels in a display such astemperature-induced color cast variations may be corrected by using abacklight unit having an array of light-emitting diodes of differentcolors. The array of light-emitting diodes may contain groups of diodesthat are yellower or are otherwise colored differently than adjacentdiodes.

An electrostatic discharge protection layer such as a layer of indiumtin oxide on a color filter layer may be grounded to a housing usingconductive tape. A radio-frequency shielding can may be shorted to theconductive tape using a layer of conductive foam.

Black display edge coatings and adhesive-based structures for mounting adisplay to a housing may be used to block stray light within a devicesuch as stray light produced by a backlight unit for a display.

A camera module or other optical component may be aligned with a camerawindow region in a display. The camera window may be formed from acircular hole or other opening in an opaque masking layer that is formedin an inactive area of a display. The camera window may lie betweeninner and outer concentric rings of sealant. The sealant may be used tolaterally confine liquid crystal material within the display. An outerring of sealant may surround the inner ring of sealant.

The display may have a color filter layer and a thin-film transistorlayer. The liquid crystal material may be formed in a layer between thecolor filter layer and the thin-film transistor layer. To preventdisplay layers such as the color filter layer and thin-film transistorlayer from bowing in the region of the display between the inner andouter rings of sealant, support structures may be formed that connectthe color filter layer and thin-film transistor layer between the innerand outer rings of sealant. The support structures may include a layerof clear adhesive in the vicinity of the camera window region.

Further features of the invention, its nature and various advantageswill be more apparent from the accompanying drawings and the followingdetailed description of the preferred embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an illustrative electronic device inaccordance with an embodiment of the present invention.

FIG. 2 is a cross-sectional side view of a portion of a display mountedin an electronic device housing using an elastomeric gasket inaccordance with an embodiment of the present invention.

FIG. 3 is a perspective view of an illustrative elastomeric gasket withan embedded stiffener in accordance with an embodiment of the presentinvention.

FIG. 4 is a perspective view of an illustrative portion of anelastomeric gasket in accordance with an embodiment of the presentinvention.

FIG. 5 is a cross-sectional side view of an illustrative elastomericgasket and associated assembly tool showing how the gasket may beinstalled within a groove between a display and electronic devicehousing in accordance with an embodiment of the present invention.

FIG. 6 is a perspective view of an illustrative roller for installing anelastomeric gasket in an electronic device in accordance with anembodiment of the present invention.

FIG. 7 is a top view of a portion of an electronic device showing how anelastomeric gasket with an embedded stiffener may be installed within anelectronic device housing around the periphery of the display inaccordance with an embodiment of the present invention.

FIG. 8 is a cross-sectional side view of display structures and anassociated polymer molding tool showing how an elastomeric gasket may bemolded to the peripheral edges of the display structures in accordancewith an embodiment of the present invention.

FIG. 9 is a perspective view of an electronic device housing with arecess that receives and surrounds a corner bracket in accordance withan embodiment of the present invention.

FIG. 10 is a cross-sectional side view of an electronic device having ahousing that is in an unflexed condition in accordance with anembodiment of the present invention.

FIG. 11 is a cross-sectional side view of the electronic device of FIG.10 in a configuration in which the housing has been flexed in accordancewith an embodiment of the present invention.

FIG. 12 is a cross-sectional side view of an illustrative electronicdevice having a gap-filling structure interposed between displaybacklight structures and housing structures in accordance with anembodiment of the present invention.

FIG. 13 is a cross-sectional side view of an adhesive and foam structurethat may be used in attaching a display to a housing in accordance withan embodiment of the present invention.

FIG. 14 is a cross-sectional side view of a portion of an electronicdevice in which an adhesive-based structure such as the adhesive andfoam structure of FIG. 13 has been used in attaching a display to theelectronic device in accordance with an embodiment of the presentinvention.

FIG. 15 is a diagram showing how a light-blocking layer may be formed onthe ground edge of a display in accordance with an embodiment of thepresent invention.

FIG. 16 is a perspective view of an illustrative electronic devicehaving a display that may be characterized by different operatingtemperatures in different regions in accordance with an embodiment ofthe present invention.

FIG. 17 is a cross-sectional side view of an illustrative display withbacklight structures in accordance with an embodiment of the presentinvention.

FIG. 18 is a top view of display structures including a light guideplate with light scattering structures configured to help compensate forspatially varying color characteristics in the display structures inaccordance with an embodiment of the present invention.

FIG. 19 is a cross-sectional side view of an illustrative display havinga conductive tape structure for grounding an electrostatic dischargeprotection layer to a housing in accordance with an embodiment of thepresent invention.

FIG. 20 is a top view of an edge portion of a display that is beingshorted to a housing structure using a conductive tape structure inaccordance with an embodiment of the present invention.

FIG. 21 is a diagram showing how a display may have multiple concentricbeads of sealant and may have a camera window in accordance with anembodiment of the present invention.

FIG. 22 is a cross-sectional side view of the display of FIG. 21 showinghow adhesive may be incorporated into the display in the vicinity of thecamera window to provide structural support for layers in the display inaccordance with an embodiment of the present invention.

FIG. 23 is a perspective view of an edge portion of a display showinghow a printed circuit may have integral flexible printed circuit tailsfor attaching display driver circuitry to a thin-film-transistor layerin the display in accordance with an embodiment of the presentinvention.

DETAILED DESCRIPTION

Electronic devices such as notebook computers, tablet computers,cellular telephones, media players, televisions, and other electronicequipment may be provided with displays.

An illustrative electronic device such as a portable computer or otherelectronic equipment that has a display is shown in FIG. 1. As shown inFIG. 1, display 14 of device 10 may be mounted in housing 12. Housing 12may be formed from a single housing structure or may, as shown in FIG.1, have multiple attached structures such as upper housing portion 12Aand lower housing portion 12B. In this type of configuration, display 14may be mounted in upper housing portion 12A (as an example).

Housing 12 may be formed from a unibody construction in which some orall of housing 12 is formed form a unitary piece of material (e.g.,metal, plastic, or fiber composite materials) or may be formed frommultiple structures that have been mounted together using adhesive,fasteners, and other attachment mechanisms. For example, housing 12 maybe formed from frame members and other internal supports to whichexternal plates, housing sidewalls, bezel structures, and otherstructures are mounted. Hinge structures 18 may be used in attachinghousings formed from multiple housing portions such as upper housingportion 12A and lower housing portion 12B.

Housing portion 12A may be used to house display 14 and may sometimes bereferred to as a display housing or lid. Display housing 12A may beattached to housing portion 12B (sometimes referred to as a main unit orbase housing) using hinge structures 18, so that display housing 12A mayrotate relative to main housing 12B around hinge axis 16. Device 10 mayinclude ports for removable media, data ports, keys such as keyboard 20,input devices such as track pad 24, microphones, speakers, sensors,status indicators lights, and other components. If desired, device 10may have a camera such as camera 26.

Display 14 may have an active portion such as active central rectangularportion 28 and an inactive portion such as inactive portion 30. Activeportion 28 of display 14 may have a shape such as a rectangular shapebounded by line 32 of FIG. 1. Inactive portion 30 of display 14 may havea rectangular ring shape or other suitable shape and may form a borderthat runs along the periphery of display 14. Display pixel arrayelements such as liquid crystal diode display pixels or other activedisplay pixel structures may be used in portion 28 to present images toa user of device 10. Inactive portion 30 is generally devoid of displaypixels and does not participate in forming images for a user. To hideunsightly internal components from view, internal components in inactiveportion 30 may be blocked from view by incorporating a black maskinglayer or other opaque masking layer into the peripheral portion ofdisplay 14.

Display 14 may be a liquid crystal display, an electrophoretic display,an electrowetting display, a plasma display, an organic light-emittingdiode display, or a display formed using other display technologies.Illustrative configurations for device 10 in which display 14 has beenformed using liquid crystal display technologies are sometimes describedherein as an example. This is, however, merely illustrative. Display 14may, in general, be formed using any suitable type of displaystructures.

Device 10 may have components that are formed in inactive display region30 such as camera 26. Camera 26 may be mounted within display housing12A and may operate through a window (sometimes referred to as a camerawindow) in display 14. The camera window may be created by forming acircular opening or an opening with another suitable shape in the layerof opaque masking material in region 30.

Housings 12A and 12B may be formed from materials such as metal (as anexample). To prevent undesired contact between the exposed inner facesof housings 12A and 12B when housing 12 has been placed in a closed-lidposition, an elastomeric material (sometimes referred to as anelastomeric gasket) may be formed on a portion of housing 12 such ashousing 12A. An elastomeric gasket may, as an example, have arectangular ring shape so that the gasket runs along line 32 of FIG. 1around the periphery of display 14. The elastomeric gasket may protrudefrom housing 12A so the elastomeric gasket forms a soft bumper structurethat prevents housings 12A and 12B from directly rubbing against eachother when housing 12A has been placed in a closed position.

A cross-sectional side view of device 10 in the vicinity of a portion ofan elastomeric gasket is shown in FIG. 2. As shown in FIG. 2, display 14may include multiple display layers such as lower polarizer layer 34,thin-film transistor layer 36, color filter layer 40, and upperpolarizer layer 42. A layer of liquid crystal material such as liquidcrystal layer 38 may be interposed between thin-film transistor layer 36and color filter layer 40. Thin-film transistor layer 36 may have anarray of electrodes and associated thin-film transistors. The electrodesand thin-film transistors may be used in controlling the application ofelectric fields to liquid crystal layer 38 to adjust the orientation ofliquid crystals in layer 38. In conjunction with upper and lowerpolarizers 34 and 42, control of the electric fields in layer 38 may beused to adjust the transmission of the display pixels in display 14 andthereby present images on display 14 for a user of device 10. Colorfilter layer 40 may include an array of color filter elements thatprovide display 14 with the ability to display color images.

Gasket 44 may be formed from a pliable (flexible) material such as anelastomeric polymer (e.g., silicone). Gasket 44 may have a recess suchas recess 56 that is configured to receive edge 50 of display 14. Recess56 may be formed between protrusion 52 on the upper portion of gasket 44and protruding portion 54 on the lower portion of gasket 44. Protrudingportions 52 and 54 and recess 56 may be configured so that gasket 44 hasa C-shaped cross section for receiving edge 50, as shown in FIG. 2.

The layers of display 14 may not all be aligned in the vicinity of edge50. For example, upper polarizer 42 may be recessed from edge 50, sothat an exposed strip of color filter layer 40 is formed such as exposedstrip 48. The presence of upper protruding portion 52 of gasket 44 mayhide region 46 of display 14 from view, thereby blocking unsightlyfeatures such as exposed color filter strip 48 from view by a user ofdevice 10.

Housing 12A may have a groove such as groove 58 that is configured toreceive gasket 44. Groove 58 may have an outer edge such as edge 60 andan inner edge such as edge 62. As shown in the exploded perspective viewof housing 12A of FIG. 3, groove 58 may have a rectangular ring shapeand may lie between inner groove edge 60 and outer edge 64 of display14. Along edge 68 of display 14, gasket 44 may have an associatedstiffener such as stiffener 66. Stiffener 66 may, for example, beembedded within the elastomeric material that forms gasket 44. Stiffener66 may be formed from metal, fiber-based composites, or other stiffmaterials. As an example, stiffener 66 may be formed from a patternedsheet metal layer such as a layer of stainless steel or aluminum orother metal member configured to add stiffness to gasket 44 along edge68 of display 14 and thereby facilitate assembly operations. Stiffener66 may be attached to gasket 44 using adhesive or stiffener 66 (e.g., apatterned sheet metal member) may be incorporated into gasket 44 bymolding elastomeric material for gasket 44 over stiffener 66 (e.g.,using compression molding equipment or injection molding equipment).

FIG. 4 is a perspective view of a portion of a corner portion of gasket44. As shown in FIG. 4, gasket 44 may include notches such as notches 70(e.g., in protruding lower edge portion 54). The presence of notches 70in gasket 44 may help provide gasket 44 with flexibility duringinstallation of gasket 44 in groove 58 and/or may help align gasket 44with housing 12A.

FIG. 5 is a cross-sectional side view of groove 58 showing how adhesive72 may be placed on lower surface 74 of groove 58. Adhesive 72 may be apressure sensitive adhesive or other adhesive for attaching gasket 44within groove 58. During installation of gasket 44, a user orcomputer-controlled equipment may press tool 78 against portion 82 ofgasket 80 in directions such as direction 80, thereby causing gasket 44to rotate so that portion 54 of gasket 44 moves into groove 58 indirection 84 and so that edge 50 of display 14 is received within gasketrecess 56 and so that surface 76 of gasket 44 lies on adhesive 72.

A tool such as roller 84 of FIG. 6 may also be used in installing gasket44 within groove 58 between housing 12A and display 14.

FIG. 7 is a top view of housing 12A showing how gasket 44 may be tapedto housing 12A along edge 68 using tape 86. Following attachment ofgasket 44 to housing 12A using tape, assembly personnel orcomputer-controlled equipment may tuck gasket 44 into grove 58 (e.g.,first tucking gasket 44 into corners 88, second tucking gasket 44 intocorner 90, third tucking gasket 44 into corner 92, and fourth tuckinggasket 44 into groove 58 along edge 94). Following these gasket tuckingoperations, a roller such as roller 84 of FIG. 6 may be used to roll theremainder of gasket 44 into groove 58 by rolling along edge 96 indirection 98, along edge 94 in direction 100, and along edge 102 indirection 104 (as an example). Other types of assembly operations may beused to install gasket 44 in groove 58 of housing 12A, if desired. Theuse of corner and edge tucking operations (e.g., using a tool such astool 78) followed by use of roller 84 is merely illustrative.

If desired, elastomeric gasket material may be attached to display 14using molding equipment (e.g., compression molding tools, injectionmolding tools, etc.). As shown by display 14 in the upper portion ofFIG. 8, for example, display 14 may initially be formed without anygasket material on edges 50. Integral peripheral gasket 108 may then beformed by molding an elastomeric polymer over edges 50 using compressionmolding tool 106 or other plastic molding equipment, as shown in thelower portion of FIG. 8. Following attachment of gasket 108 to display14, display 14 may be installed in housing 12A.

Housings 12A and 12B may be formed from a metal such as aluminum. Tostructurally reinforce the corners of housing 12 (e.g., housing 12A),housing 12A may be provided with corner brackets such as corner bracket110 of FIG. 9. Corner brackets such as corner bracket 110 may beprovided at each of the four corners of housing 12A (as an example).Corner brackets such as corner bracket 110 may be formed from a materialsuch as a stainless steel that is stronger than aluminum and whichtherefore adds structural strength to housing 12A. The additionalstrength provided by corner brackets 110 may help device 10 avoid damage(e.g., to display 14) when a corner of device 10 strikes an externalobject during an unintentional drop event. Each corner bracket may beformed from a planar sheet metal member and may have opposing surfacessuch as upper surface 111 and lower surface 113, surrounded byperipheral edge 115.

As shown in FIG. 9, housing 12A may have a rear surface such as rearsurface 121. Raised edge portions such as inner rib 118 and outer rib116 may surround a rectangular center portion of rear housing wall 121.When fully assembled, display 14 may be cover inner rib 118 and outerrib 116. Portions of inner rib 118 and outer rib 116 may be configuredto form corner recesses such as corner recess 112. Corner recess 112 mayhave a shape that is configured to receive corner bracket 110.Adhesive-based attachment structures 120 or other suitable fasteningmechanisms may be used to help retain corner bracket 110 within cornerrecess 112, if desired.

Corner recess 112 may have a planar surface that is configured to matewith lower surface 113 of corner bracket 110. Adhesive 120 may beinterposed between surface 113 and the surface of recess 112. Thesurface of recess 112 may be surrounded by inner recess edge 117. Theshape of edge 117 may be configured to match the shape of edge 115, sothat edge 117 may receive edge 115 and corner bracket 110. When bracket110 is mounted within housing 12A, housing 12A may surround bracket 110on all sides (e.g., peripheral edge 115 of bracket 110 may be surroundedby portions of housing 12A along edge 117).

FIG. 10 is a side view of device 10 showing how display 14 may beattached to display housing 12A using an adhesive-based structure oninner rib 118 (e.g., a rectangular ring of adhesive-based materials). Inthe configuration of FIG. 10, device housing 12A has not been subjectedto a drop event and is therefore unflexed and planar. If dropped, devicehousing 12A may flex, so that edge portions 122 of housing 12A move indirections 124 away from display 14. By locating adhesive-basedattachment structures on inner ribs 118 but not on outer ribs 116 (i.e.,so that outer ribs 116 are free of adhesive), downward force from ribs116 pulling on display 14 can be eliminated, thereby reducing stress ondisplay 14 and helping to avoid damage to display 14 in a drop event.

FIG. 12 is a cross-sectional side view of device 10 showing how display14 may be provided with backlight illumination using backlight unit 126.Backlight unit 126 may include light guide plate 148, optical films 150,and reflector 152. When backlight unit 126 is operating, backlight 136may travel in direction Z through display 14 so that user 138 may viewbacklit images on display 14. Backlight unit 126 may be mounted on aledge such as ledge 128 of housing 12A. In region 140, the shape ofhousing 12A may be configured so that there is a gap G between lower(innermost) surface 132 of backlight unit 126 (i.e., the lower surfaceof reflector 152) and upper (innermost) surface 130 of the rear housingwall in housing 12A. The size of gap G may be, for example, 1-10 mm, 1-5mm, less than 4 mm, less than 2 mm, 0.5 to 3 mm, or other suitable size.

During use of device 10, housing 12A and display 14 may be subjected todrop events and other forces that may cause display 14 to bow downwardin direction 142. To prevent lower surface 132 of backlight unit 126(i.e., the lower surface of reflector 152) from incurring damage bycontacting inner surface 130 of display housing 12A, a gap fillingstructure such as gap filing structure 134 may be interposed betweenbacklight unit 126 and the rear housing wall formed by the portion ofhousing 12A in region 140. Gap filling structure 130 may have the shapeof a rectangle (when viewed in direction 142) and may have a footprintthat approximately matches that of backlight unit 126. Examples ofmaterials that may be used for forming gap filling structure 134(sometimes referred to as a dome filler) are plastic, foam, structuresthat includes one or more layers of plastic and/or foam, plasticstructures with cavities separated by ribs, etc. Gap filling structure126 may have a lip such as lip 144 that rests on ledge 146 in housing12A or may be formed from a rectangular structure (e.g., a rectangularsheet of foam).

FIG. 13 is a cross-sectional side view of display 14 in device 10 in thevicinity of adhesive-based attachment structure 120. As shown in FIG.13, adhesive-based structure 120 may include multiple layers of materialsuch as black adhesive layer 155, black foam layer 156, and blackadhesive layer 158. Due to the presence of foam layer 156, structures120 may become compressed during an impact event or otherstress-producing event, thereby relieving stress from display 14. Byusing opaque materials in forming adhesive-based attachment structures120, light from display 14 (e.g., stray backlight from display backlightunit 126) may be blocked, thereby reducing light leakage in device 10.

As shown in FIG. 14, for example, backlight unit 126 may emit straylight 160. Adhesive-based attachment structure 120 may be formed fromblack layers of material or other opaque materials that block light 160and thereby help reduce stray light in display 14 and device 10. Somestray light may reach the edges of display 14 by traveling throughdisplay layers such as color filter layer 40 and thin-film transistorlayer 36. When this stray light reaches edge 50 of display 14, there isa potential that surface roughness on edge 50 will cause the stray lightto be scattered out of display edge 50 into locations that might bevisible to a user of device 10. To reduce the emission of stray lightfrom edge 50, edge 50 may be coated with an opaque material such asmaterial 162. Material 162 may coat edge 50 without coating adjacentexposed upper and lower surfaces of display 14 (as shown in FIG. 14) ormay, if desired, cover parts of the nearby upper and lower surface ofdisplay 14. Light-blocking coating 162 may be formed from ink (e.g.,black ink) or other opaque materials.

An illustrative process for forming light-blocking structure 162 on edge50 of display 14 is shown in FIG. 15. As shown in FIG. 15, an opaquemasking layer such as masking layer 164 (e.g., a black masking layer)may be interposed between color filter layer 40 and thin-film transistorlayer 36 near the edge of display 14 (e.g., in inactive region 30). Asinitially formed as part of the process of attaching layers 40 and 36 toeach other, the outer edge of opaque masking layer 164 may not bealigned with the edges of color filter layer 40 and thin-film transistorlayer 36. Display layers such as layers 40 and 36 may be formed fromtransparent substrate materials such as plastic or glass. Using grindingequipment such as grinding tool 166, the exposed edges of display 14 maybe ground until exposed color filter edge 174, exposed opaque maskinglayer edge 170, and thin-film transistor edge 172 are aligned relativeto lateral dimension 176 (which lies in the plane of display 14).Coating tool 176 may then be used to deposit an opaque coating on theedge of display 14 to form light-blocking structure 162. In arectangular display with four edges, light-blocking coatings such aslight-blocking structure 162 of FIG. 15 may be formed on all four edgesof display 14 or on a subset of the four edges of display 14.

Housing 12B may contain components that generate heat such as amicroprocessor, video chips, communications circuits, memory,application-specific integrated circuits, power supply components, andother circuitry. This circuitry may be cooled using circulated air. Asan example, housing 12B may contain fan-based cooling structures such asstructures 182 that draw cool air 178 into housing 12B from thesurrounding environment and that expel corresponding heated air 184. Asshown in FIG. 16, heated air 184 may tend to heat regions 186 of display14 more than other regions of display 14. This may tend to affect thecolor performance of display 14. In particular, in the absence ofcorrective action, the display pixels and therefore the image content ondisplay 14 in heated areas such as heated areas 186 may have a bluishcolor cast relative other areas of display 14.

To compensate for the excessively blue color of the display pixels inregions such as regions 186 that are experiencing elevated temperaturesduring operation of device 10, display 14 may be backlit using an arrayof light-emitting diodes of different colors such as yellowishlight-emitting diodes and white light-emitting diodes. The backlightunit in display 14 may also be provided with a light guide platescattering pattern that helps scatter backlight out of display 14 in apattern that directs an enhanced amount of yellowish light throughregions 186 and thereby compensates for the bluish color in regions 186.

A cross-sectional side view of a backlight arrangement of the type thatmay be used in display 14 is shown in FIG. 17. As shown in FIG. 17,light 188 may be generated by a light source such as light source 190.Light 188 may be launched into edge 192 of light guide plate 148. Lightguide plate 148 may be formed from transparent plastic (as an example).Light 188 may be distributed throughout light guide plate 148 in the X-Yplane due to the principal of total internal reflection. Light thatscatters from features such as light-scattering features 154 maypropagate upwards in direction Z as backlight 136. Backlight 136 maypass through display 14 and may help user 194 view images on display 14.A reflective layer such as reflector 152 may reflect light that hasscattered downwards back in upwards direction Z, thereby enhancingbacklight efficiency. Optical films 150, which may be interposed betweenlight guide plate 148 and display 14 may include a diffusing layer andlight-collimating layer (as examples).

Light source 190 may be formed from an array of light-emitting diodesmounted on a flexible printed circuit or other substrate. The array oflight-emitting diodes may extend along edge 192 of light guide plate 148in dimension X. To help compensate display 14 for temperature-inducedcolor variations or other location-based color variations, the color ofthe light-emitting diodes may be varied as a function of dimension X.The light scattering efficiency of light-scattering structures 154 mayalso be varied as a function of location in display 14 (i.e., dimensionsX and Y). Light-scattering structures 154 may, as an example, be formedfrom pits in the surface of light guide plate 148 (e.g., laser-etchedpits having a diameter of about 10-16 microns). To adjust the lightscattering efficiency of light-scattering structures 154, the density oflight-scattering structures 154 (i.e., the number of structures 154 perunit area), the size of light-scattering structures 154, and/or theshape of light-scattering structures 154 may be varied.

FIG. 18 is a top view of display 14 showing how light-emitting diodes190 may be organized in a line parallel to edge 192 of light guide plate148. Light-emitting diodes 190 may be mounted on a substrate such asflexible printed circuit 196 (e.g., a sheet of polyimide or a layer ofother flexible polymer). Light-emitting diodes 190 may emit light 188that is coupled into edge 192 of light guide plate 148. When travelingthrough light guide plate 148, light 188 will be scattered in dimensionZ by light-scattering structures 154 to serve as backlight for display14.

As shown in FIG. 18, different light-emitting diodes 190 may be providedwith different colors. In particular the light-emitting diodes labeled“W” may emit light that is white, whereas the groups of light-emittingdiodes labeled “Y” may emit light that is more yellow than thelight-emitting diodes labeled “W”. The white emitting diodes labeled “W”(i.e., the light-emitting diodes that are adjacent to the groups ofyellow light-emitting diodes) may be aligned (in dimension X) withportions (i.e., vertically extending regions) of display 14 that are notelevated in temperature and that therefore operate satisfactorily withnormal (e.g., white-light) illumination.

In regions 186, the operating temperature of display 14 is elevated,which causes the display pixels to tend to exhibit light with a bluishcolor. To compensate for the overly-blue tendencies of the displaypixels in regions 186, light-emitting diodes 190 that are aligned (indimension X) with elevated temperature regions 186 (i.e., the “Y” lightemitting diodes of FIG. 18) may emit light that is yellowish relative tothe light emitted by the white light-emitting diodes. The presence ofyellowish light 188 in regions 186 will tend to counteract the inherentbluish cast of the display pixels in regions 186 due to the elevatedtemperature in regions 186.

There is generally a decrease in light intensity for light 188 as afunction of distance Y into light guide plate 148. To counteract thislight intensity drop-off, light-scattering structures 154 may beprovided with a light-scattering efficiency that increases withincreases in dimension Y. This increase in light-scattering efficiencyas a function of increasing Y value is illustrated by the enhanceddensity of light-scattering structures 154 with increases in dimension Yin FIG. 18. Within regions 186, extra yellow light may be scatteredtowards the viewer to compensate for the bluish color cast of thedisplay pixels in regions 186 by providing light-scattering structures154′ in regions 186 with more light scattering efficiency thancomparable light-scattering structures 154 (i.e., light-scatteringstructures 154 in laterally adjacent portions of display 14). With thisconfiguration, more efficiency is provided to light-scatteringstructures 154′ in regions 186 than structures 154 that are located atthe same location in dimension Y but that are offset in dimension X soas to fall outside of regions 186. As a result of using a pattern oflight-scattering structures that exhibit localized increases inlight-scattering efficiency, luminance (light intensity) may not becompletely uniform on display 14. Nevertheless, because the human eye ismore sensitive to color variations than luminance variations, the use ofcompensating light-emitting diode colors and light-scattering structures154′ with locally enhanced light-scattering efficiencies tends toimprove perceived display performance.

Display 14 may include a conductive layer such as a layer of indium tinoxide (ITO) for providing protection from damage due to electrostaticdischarge events. When a finger of a user or other external object comesinto contact with the outer surface of display 14 such as outer surface198 of display 14 of FIG. 19, there is a risk for undesired staticcharge accumulation that could disrupt the electric fields within liquidcrystal layer 38. Conductive layer 200 (e.g., an indium tin oxide layeror other transparent conductive electrostatic discharge protectionlayer) may be used to prevent events of this type from disruptingdisplay operation. As shown in FIG. 19, conductive layer 200 may beinterposed between upper polarizer layer 198 and color filter layer 40.

In edge region 222, a strip of conductive layer 200 may be exposed(i.e., not covered with polarizer layer 198). This allows a conductivepath to be formed between conductive layer 200 and a source of groundsuch as metal housing structure 12A. Conductive layer 204 may be, forexample, a layer of metal tape. Conductive adhesive 202 may be used toattach conductive tape 204 to conductive layer 200 in region 222.Conductive adhesive 206 may be used to attach portion 220 of conductivetape structure 204 to housing 12A. Housing 12A may, if desired, beformed from a metal that has an insulating coating such as aluminumcovered with an insulating coating of aluminum oxide. As shown in FIG.19, laser etching or machining operations may be used to create uncoatedregion 224 on housing 12A to ensure that oxide or other insulatingmaterials do not degrade the quality of the electrical connection formedbetween portion 220 of structure 204 and housing 12A. If desired,fasteners, welds, connectors, or other electrical attachment mechanismsmay be used in forming electrical connections between the ends ofconductive tape structure 204 and conductive structure 200 and housing12A. The use of conductive adhesive in forming these connections in theconfiguration of FIG. 19 is merely illustrative.

Thin-film transistor layer 36 may have a portion such as thin-filmtransistor ledge 210 that is uncovered by color filter layer 40. Displaydriver integrated circuits such as circuit 208 may be mounted on ledge210. Ancillary display circuits such as display circuit 214 may bemounted on other substrates such as printed circuit 212. Printed circuit212 may be a rigid printed circuit board (e.g., a layer offiberglass-filled epoxy) or may be a flexible printed circuit (e.g., aprinted circuit formed from a flexible sheet of polyimide or otherflexible polymer). Radio-frequency electromagnetic signal shieldingstructures such as metal shielding can 216 may be grounded to groundtraces on printed circuit 212 and may be used to cover and shieldcircuitry 214. Conductive foam 218 may be interposed between shield can216 and conductive tape structure 204. As shown in FIG. 19, can 216 maybe shorted to portion 220 of structure 205 using conductive foam 218.

A top view of conductive tape structure 20 of FIG. 19 is shown in FIG.20.

FIG. 21 is a front view of display 14 showing how rings of sealant maybe used in sealing liquid crystal material 38 within display 14. Asshown in FIG. 21, a bead of sealant such as sealant bead 226 may runaround the periphery of display 14 between color filter layer 40 andthin-film transistor layer 36. The bead of sealant may have a cross-overregion such as region 240, so that a single line of sealant may forminner and outer concentric rings of sealant such as outer ring 228 andinner ring 230. By using sealant 226, liquid crystal material 38 may belaterally sealed within the cavity formed between color filter layer 40and thin-film transistor layer 36. The layer of liquid crystal materialthat is interposed between color filter layer 40 and thin-filmtransistor layer 36 may have a thickness of about 3-5 microns, about1-10 microns, more than 3 microns, less than 5 microns, or othersuitable thickness.

Liquid crystal material 38 may be confined within the rectangular regiondefined by sealant structures 226 (i.e., inner sealant ring 230 may runalong the periphery of rectangular liquid crystal material layer 38 inactive display region 28). A gap such as gap GP may be formed betweenouter ring 228 and inner ring 230. Gap GP may be free of active displaypixels (i.e., gap GP may lie in inactive display region 30) and may ormay not contain liquid crystal material.

To prevent display layers such as color filter layer 40 and thin-filmtransistor layer 36 bowing in gap region GP and thereby formingundesired Newton's rings that may be visible to a user, a supportstructure such as a structure formed from a supportive layer of materialmay be formed in regions such as region 234 (and if desired, in otherportions of gap GP running around the periphery of display 14). Thesupportive layer of material in region 234 (and, if desired, otherportions of gap GP between rings 228 and 230) may be formed from a layerof adhesive.

Spacers 232 may have a defined height in dimension Z (e.g., 3-5 micronsor other suitable height). When color filter layer 40 and thin-filmtransistor layer 36 are attached to each other, spacers 232 (which mayalso be formed in the array of display pixels for display 14 withinliquid crystal material 38) may ensure that the spacing between layer 40and layer 36 has a well-defined thickness during the introduction of thelayer of adhesive in liquid form. Spacers 232 may be formed from columnsof polymer (e.g., columns of polyimide patterned usingphotolithography).

The adhesive may be a clear ultraviolet-light-curable liquid adhesivethat flows between layers 40 and 36 around spacers 232. The liquidadhesive may be cured by applying ultraviolet light through thin-filmtransistor layer 36. Once cured, the clear liquid adhesive may becomerigid and may fill the space between layers 40 and 36 with a solidsupport structure that prevents layers 40 and 36 from bowing relative toeach other. Use of a clear material for the adhesive in region 234 mayallow light for camera 26 or other optical components to pass throughthe adhesive.

A cross-sectional side view of display 14 in the vicinity of camera 26is shown in FIG. 22. The cross-sectional side view of FIG. 22 is takenalong line 236 and is viewed in direction 238 of FIG. 21. As shown inFIG. 22, color filter layer 40 and thin-film transistor layer 36 may beseparated by a thickness T (e.g., a thickness of 3-5 microns, 1-10microns, more than 3 microns, less than 5 microns, or other suitablethickness). Liquid crystal material 38 may be interposed between colorfilter layer 40 and thin-film transistor layer 36 in active area 28.Sealant may prevent liquid crystal material 38 from escaping from theedges of display 14 in dimensions X and Y.

An opaque masking layer such as opaque masking layer 164 may be formedon the underside of color filter layer 40 in inactive region 30. Opaquemasking layer 164 may block internal display structures from view by auser. For example, opaque masking layer 164 may block sealant rings 228and 230 from view.

Camera 26 may include a camera module such as camera module 241(sometimes referred to as a camera). Camera module 241 may have adigital image sensor such as image sensor 244 and lens structures 242.Lens structures 242 and image sensor 244 may be aligned with opening 248in opaque masking layer 164, so that image light 246 for digital imagesmay be captured by camera module 241. Opening 248 may sometimes bereferred to as a camera window. The shape of opening 248 may be, forexample, a circle that is aligned with a circular lens in lensstructures 242.

Sealant rings 228 and 230 may be separated by a gap such as gap GP. Tosupport color filter layer 40 and thin-film transistor layer 36 withingap GP, adhesive 250 may be interposed between color filter layer 40 andthin-film transistor layer 36 within gap GP. Adhesive 250 may be a clearadhesive that allows light 246 associated with an image to pass throughgap GP to camera module 241. If desired, a keep-out zone (e.g., acircular region overlapping lens 242) may be used to prevent adhesive250 from filling the portion of gap GP that lies directly above lens242. In configurations of the type shown in FIG. 22 in which adhesive250 fills substantially all of gap GP in the vicinity of camera module241 (e.g., when adhesive 150 fills gap GP at least within region 234 ofFIG. 21), adhesive 250 may serve as an index-matching structure thathelps to reduce reflections from the surface of layers 40 and 36 andthereby improve camera performance.

As shown in the perspective view of display 14 of FIG. 23, display 14may be controlled using display driver integrated circuits such asintegrated circuits 254 on thin-film transistor ledge 210 and integratedcircuits 256 (e.g., timing circuits) on printed circuit structure 252.Printed circuit structure 252 may be formed from a rigid printed circuitsubstrate (e.g., a fiberglass-filled epoxy substrate or other rigiddielectric substrate). Integral flexible printed circuit tail 258 mayprotrude from rigid printed circuit substrate 252. With this type of“rigid flex” board, components 256 may be mounted on a rigid printedcircuit substrate structure, whereas conductive traces on flexibleprinted circuit portion 258 such as traces 260 may be used in formingelectrical connections between integrated circuits 256 and integratedcircuits 254 on thin-film transistor ledge 210. Conductive adhesive orother suitable conductive attachment structures may be used to formelectrical connections between the traces on flexible printed circuittail 258 and corresponding traces on the surface of thin-film transistorlayer 36. Traces on the surface of thin-film transistor layer 36 may beused to interconnect traces 260 and circuitry 256.

The foregoing is merely illustrative of the principles of this inventionand various modifications can be made by those skilled in the artwithout departing from the scope and spirit of the invention.

What is claimed is:
 1. An electronic device, comprising: a housinghaving at least one surface; a display mounted in the housing; backlightstructures in the housing that are configured to provide light for thedisplay; and an adhesive-based structure configured to attach thedisplay to the surface, wherein the adhesive-based structure isconfigured to prevent leakage of the light.
 2. The electronic devicedefined in claim 1 wherein the adhesive-based structure comprises blackadhesive.
 3. The electronic device defined in claim 2 wherein theadhesive-based structure comprises a first layer of adhesive attached tothe display, a second layer of adhesive attached to the surface, and alayer of foam interposed between the first and second layers ofadhesive.
 4. The electronic device defined in claim 3 wherein the firstand second layers of adhesive comprise black adhesive and wherein thelayer of foam comprises black foam, wherein the display has arectangular periphery, and wherein the adhesive-based structure runsalong the rectangular periphery.
 5. The electronic device defined inclaim 1 wherein the display has at least one display layer with an edgeand wherein the electronic device further comprises an opaque coating onthe edge.
 6. The electronic device defined in claim 1 wherein thehousing has at least one rectangular rib and wherein the surfacecomprises a surface on the rectangular rib.
 7. The electronic devicedefined in claim 6 wherein the at least one rectangular rib defines arecess, the electronic device further comprising: a stiffener in therecess.
 8. The electronic device defined in claim 7 wherein thestiffener comprises a metal bracket.
 9. An electronic device,comprising: a housing; a display mounted in the housing, wherein thedisplay has opposing outer and inner surfaces surrounded by a peripheraledge; a backlight unit configured to emit light; and an opaque coatingon the peripheral edge of the display that is configured to block someof the light to reduce light leakage from the display.
 10. Theelectronic device defined in claim 9 wherein the display includes acolor filter layer with a peripheral edge, wherein the display includesa thin-film transistor layer with a peripheral edge, and wherein theperipheral edges of the color filter layer and the thin-film transistorlayer are covered by the opaque coating.
 11. The electronic devicedefined in claim 10 wherein the display further comprises an opaquemasking layer interposed between the color filter layer and thethin-film transistor layer in an inactive region of the display, whereinthe opaque masking layer has a peripheral edge that is aligned with theperipheral edge of the color filter layer and the peripheral edge of thethin-film transistor layer, and wherein the opaque coating covers theedge of the opaque masking layer.
 12. The electronic device defined inclaim 9 further comprising: an adhesive-based structure configured toblock some of the light to reduce light leakage from the display,wherein the adhesive-based structure includes a layer of foam interposedbetween first and second layers of adhesive and wherein theadhesive-based structure is configured to attach the display to thehousing.
 13. The electronic device defined in claim 12 wherein theadhesive-based structure runs along at least one edge of the display.14. An electronic device, comprising: a display configured to operatewith first regions at a first temperature and second regions at a secondtemperature that is elevated with respect to the first temperature; anda backlight unit for the display that is configured to produce lightthat backlights the display, wherein the backlight unit includes a lightsource that produces the light and a light guide plate having an edgethat receives the light from the light source, wherein the light sourcecomprises an array of light-emitting diodes running along an edge of thelight guide plate, and wherein the light-emitting diodes are configuredto emit the light with a pattern of colors configured to compensate fordisplay color variations between the first and second regions.
 15. Theelectronic device defined in claim 14 wherein the backlight unitcomprises first light-emitting diodes that are configured to emit thelight into the light guide plate along the first regions and secondlight-emitting diodes that are configured to emit the light into thelight guide plate along the second regions and wherein the secondlight-emitting diodes are configured to emit light that has a differentcolor cast than the first light-emitting diodes.
 16. The electronicdevice defined in claim 14 wherein the second regions contain displaypixels with a bluish color cast relative to display pixels in the firstregions and wherein the second light-emitting diodes are configured toemit light that is yellower than the first light-emitting diodes. 17.The electronic device defined in claim 14 wherein the light-emittingdiodes include two groups of light-emitting diodes that are aligned withat least two portions of the second regions and includes a plurality ofadjacent light-emitting diodes along the edge and wherein the two groupsof light-emitting diodes emit light that is yellower than the adjacentlight-emitting diodes.
 18. The electronic device defined in claim 14wherein the light guide plate includes light-scattering structures thatare configured to scatter the light from the light guide plate, whereinthe first and second regions include the light-scattering structures,and wherein at a given distance from the edge, the second regionscontain light-scattering structures that exhibit a larger lightscattering efficiency than the light-scattering structures in the firstregions.
 19. The electronic device defined in claim 14 furthercomprising fan structures that are configured to blow hotter air ontothe display in the second regions than the first regions.
 20. Theelectronic device defined in claim 19 wherein the fan structures aremounted in a base housing and wherein the display is mounted in a lidhousing that is configured to rotate relative to the base housing.